JP2018107900A - Battery charge circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery charge circuit capable of precisely controlling a battery charge current.SOLUTION: A controller 22 acquires, prior to charge start, a first duty by on-off control of an element Q3 that makes a current value by a sensor S1 in a state where an element Q2 is controlled a specified value, a second duty by on-off control of an element Q5 that makes a current value by a sensor S1 a specified value, a third duty by on-off control of an element Q4 that makes a current value by the sensor S1 in a state where an element Q1 is controlled a specified value, and a fourth duty by on-off control of an element Q6 that makes a current value by the sensor S1 a specified value. After charge start, the controller performs on-off control of the elements Q3 and Q5 while correcting them by the first and second duties, and performs on-off control of the elements Q4 and Q6 while correcting them by the third and fourth duties.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a battery charging circuit for charging a battery in a motor drive system including a motor that is driven and controlled by a three-phase inverter using the battery as a power source.

  A battery charging circuit is disclosed in Patent Document 1, which is a motor driving system battery charging circuit including a three-phase motor that is driven and controlled by a three-phase inverter using a battery as a power source. A connection point of a set of switching elements constituting one phase is connected to a secondary output terminal of a single phase output. Then, in the three-phase inverter, one set of switching elements constituting one phase connected to the transformer is held in an off state, and at least one of the other two sets of switching elements is turned on / off. By controlling, the battery can be charged. Here, the battery can also be charged by performing on / off control of two sets of switching elements constituting two phases of the three-phase inverter that are not connected to the transformer.

JP 2011-211889 A

  By the way, in the case where two sets of switching elements constituting two phases that are not connected to the transformer of the three-phase inverter are controlled on and off in synchronization, it is conceivable to provide a current sensor for each phase. However, if a current sensor is attached to only one of the two phases to be controlled on / off, the two-phase current cannot be controlled equally due to variations in the dead time between the switching elements. An error occurs.

  An object of the present invention is to provide a battery charging circuit capable of accurately controlling a battery charging current.

  In the first aspect of the invention, the first switching element for the upper arm of the first phase, the second switching element for the lower arm of the first phase, the third switching element for the upper arm of the second phase, the second Drive-controlled using a battery as a power source by a three-phase inverter having a fourth switching element for the lower arm of the phase, a fifth switching element for the upper arm of the third phase, and a sixth switching element for the lower arm of the third phase A battery driving circuit of a motor drive system comprising a three-phase motor, connected to one terminal of a single-phase output transformer and a secondary side output of the single-phase output transformer, the three-phase inverter and the A rectifier circuit connected in parallel to the battery, and a connection point between the first switching element and the second switching element in the three-phase inverter is connected to the secondary output. Wiring connected to the other terminal, and during charging, the first switching element and the second switching element are held in an off state, and the third switching element and the fifth switching element are synchronously turned on / off. A control device that controls on / off of the fourth switching element and the sixth switching element in synchronization; and a current sensor that detects a current flowing between the connection point and the three-phase motor. Before starting charging, the apparatus sets a current value by the current sensor in a state in which the second switching element is controlled to a specified value, a first duty by ON / OFF control of the third switching element, and a current value by the current sensor The second duty by the on / off control of the fifth switching element and the first switch A third duty by on / off control of the fourth switching element for setting the current value by the current sensor in a state in which the control element is controlled and a current value by the current sensor to a specified value. A fourth duty is obtained by on / off control, and after charging is started, the third switching element and the fifth switching element are on / off controlled while being corrected by the first duty and the second duty. In summary, the fourth switching element and the sixth switching element are controlled to be turned on / off while being corrected by the third duty and the fourth duty.

  According to the first aspect of the present invention, the control device controls the third switching element on / off control to set the current value of the current sensor in a state in which the second switching element is controlled before the start of charging to a specified value. The first duty and the second duty by the on / off control of the fifth switching element for setting the current value by the current sensor to the specified value, and the fourth value for setting the current value by the current sensor in a state in which the first switching element is controlled to the specified value. A third duty by the on / off control of the switching element and a fourth duty by the on / off control of the sixth switching element that sets the current value by the current sensor to a specified value are acquired. Then, after the start of charging, the control device performs on / off control while correcting the third switching element and the fifth switching element with the first duty and the second duty, and controls the fourth switching element and the sixth switching element. On / off control is performed while correcting by the third duty and the fourth duty. As a result, the battery charging current can be controlled with high accuracy.

  According to a second aspect of the present invention, in the battery charging circuit according to the first aspect, the control device determines a current value by the current sensor in a state in which the second switching element is controlled before the start of charging. The fifth duty by ON / OFF control of the third switching element is set to a specified value different from that for acquiring the duty, and the current value by the current sensor is set to a specified value different from that for acquiring the second duty. The sixth duty by ON / OFF control of the fifth switching element and the current value by the current sensor in a state in which the first switching element is controlled are set to a specified value different from that when the third duty is acquired. The fourth duty by the on / off control of the four switching elements and the current value by the current sensor are set to the fourth duty. The eighth duty is obtained by the on / off control of the sixth switching element, which is set to a specified value different from that for obtaining the tee, and after the start of charging, the third switching element and the fifth switching element are On / off control is performed while correcting by the first duty, the second duty, the fifth duty, and the sixth duty, and the fourth and sixth switching elements are controlled by the third duty and the fourth duty. The on / off control may be performed while correcting with the seventh duty and the eighth duty.

  According to the present invention, the battery charging current can be accurately controlled.

The circuit diagram of the battery forklift in embodiment. Explanatory drawing of the current pathway at the time of charge. Explanatory drawing of the current pathway at the time of charge. Explanatory drawing of the electric current path before charge start. Explanatory drawing of the electric current path before charge start. The characteristic view which shows the relationship between the electric current command value and correction value for demonstrating another example.

  Hereinafter, an embodiment in which the present invention is embodied in a battery forklift will be described with reference to the drawings. The battery forklift includes, as a motor drive system, a traveling motor and a cargo handling motor that use a battery as a power source and are controlled by an inverter. The battery charging circuit uses a coil for a traveling motor and a cargo handling motor or a switching element of an inverter as a component.

  As shown in FIG. 1, the battery forklift includes an in-vehicle device 10. The in-vehicle device 10 includes a traveling motor 11 and a cargo handling motor 17 as a three-phase motor that uses a battery 30 as a power source. A traveling inverter 12 as a three-phase inverter is provided between the traveling motor 11 and the battery 30, and a cargo handling inverter 18 as a three-phase inverter is disposed between the cargo handling motor 17 and the battery 30. Is provided.

  The in-vehicle device 10 includes a Scott transformer 13 as a single-phase output transformer connected to a three-phase AC power source 40. The Scott transformer 13 has primary windings 13a and 13b and secondary windings 13c and 13d.

  Inverters 12 and 18 have first switching elements Q1 and Q11 for the upper arm of the V phase as the first phase, and second switching elements Q2 and Q12 for the lower arm of the V phase. Inverters 12 and 18 have third switching elements Q3 and Q13 for the upper arm of the W phase as the second phase, and fourth switching elements Q4 and Q14 for the lower arm of the W phase. Inverters 12 and 18 have fifth switching elements Q5 and Q15 for the upper U-phase arm as the third phase, and sixth switching elements Q6 and Q16 for the lower U-phase arm. A motor drive system battery charging circuit including motors 11 and 17 that are driven and controlled by the inverters 12 and 18 using the battery 30 as a power source.

  A traveling inverter 12 is connected to the secondary winding 13 c, which is one single-phase output of the Scott transformer 13, via a rectifier circuit 14, and a traveling motor 11 is connected to the traveling inverter 12. As the traveling motor 11, a three-phase AC motor in which coils 23, 24 and 25 are delta-connected is used. A cargo handling inverter 18 is connected to the secondary winding 13 d which is the other single-phase output of the Scott transformer 13 via a rectifier circuit 19, and a cargo handling motor 17 is connected to the cargo handling inverter 18. As the cargo handling motor 17, a three-phase AC motor in which coils 26, 27, and 28 are delta-connected is used.

  The rectifier circuit 14 is composed of a series circuit of two diodes D1 and D2, and a terminal 15a of the secondary winding 13c, which is one single-phase output of the Scott transformer 13, is connected to the middle point of both diodes D1 and D2. ing. Further, the positive side of the rectifier circuit 14 is connected to the positive electrode of the battery 30, and the negative side of the rectifier circuit 14 is connected to the negative electrode of the battery 30.

  The traveling inverter 12 includes a first switching element Q1, a third switching element Q3, and a fifth switching element Q5 as three-phase upper arm switching elements, and a second switching element Q2 as a lower arm switching element. A three-phase inverter provided with a fourth switching element Q4 and a sixth switching element Q6 is used. MOSFETs are used for the switching elements Q1 to Q6. The first switching element Q1 and the second switching element Q2, the third switching element Q3 and the fourth switching element Q4, the fifth switching element Q5 and the sixth switching element Q6 are respectively connected in series. The drains of switching elements Q1, Q3, and Q5 are connected to the positive electrode of battery 30, respectively, and the sources of switching elements Q2, Q4, and Q6 are connected to the negative electrode of battery 30, respectively. Each of the switching elements Q1 to Q6 has a parasitic diode D connected between the drain and the source in antiparallel, that is, in a state where the cathode corresponds to the drain and the anode corresponds to the source.

  A connection point A (a connection point between the source of the first switching element Q1 and the drain of the second switching element Q2), which is the midpoint between the first switching element Q1 and the second switching element Q2, is for traveling through the current sensor S1. The motor 11 is connected to a connection point between the coil 23 and the coil 24. The midpoint of the third switching element Q3 and the fourth switching element Q4 (the connection point between the source of the third switching element Q3 and the drain of the fourth switching element Q4) is the coil 24 of the traveling motor 11 via the current sensor S2. And a connection point between the coil 25 and the coil 25.

  The midpoint of the fifth switching element Q5 and the sixth switching element Q6 (the connection point between the source of the fifth switching element Q5 and the drain of the sixth switching element Q6) is the connection between the coil 23 and the coil 25 of the travel motor 11. Connected to a point. The connection point A between the source of the first switching element Q1 and the drain of the second switching element Q2 is connected to the rectifier circuit 14 in the secondary winding 13c which is one single-phase output of the Scott transformer 13 by the wiring 20. It is connected to the terminal 15b opposite to the terminal 15a.

  The rectifier circuit 19 is composed of a series circuit of two diodes D3 and D4, and the terminal 16a of the secondary winding 13d which is the other single-phase output of the Scott transformer 13 is connected to the middle point between the diodes D3 and D4. ing. The positive side of the rectifier circuit 19 is connected to the positive electrode of the battery 30, and the negative side of the rectifier circuit 19 is connected to the negative electrode of the battery 30.

  The cargo handling inverter 18 includes a first switching element Q11, a third switching element Q13, a fifth switching element Q15 as three-phase upper arm switching elements, and a second switching element Q12 as a lower arm switching element. A three-phase inverter provided with a fourth switching element Q14 and a sixth switching element Q16 is used. MOSFETs are used for the switching elements Q11 to Q16. The first switching element Q11 and the second switching element Q12, the third switching element Q13 and the fourth switching element Q14, the fifth switching element Q15 and the sixth switching element Q16 are respectively connected in series. The drains of switching elements Q1, Q3, and Q5 are connected to the positive electrode of battery 30, respectively, and the sources of switching elements Q2, Q4, and Q6 are connected to the negative electrode of battery 30, respectively. Each of the switching elements Q11 to Q16 has a parasitic diode D connected between the drain and the source in antiparallel, that is, in a state where the cathode corresponds to the drain and the anode corresponds to the source.

  A connection point (a connection point between the source of the first switching element Q11 and the drain of the second switching element Q12) B, which is the midpoint between the first switching element Q11 and the second switching element Q12, is used for cargo handling via the current sensor S11. The motor 17 is connected to a connection point between the coil 26 and the coil 27. The midpoint of the third switching element Q13 and the fourth switching element Q14 (the connection point between the source of the third switching element Q13 and the drain of the fourth switching element Q14) is the coil 27 of the cargo handling motor 17 via the current sensor S12. And a connection point between the coil 28 and the coil 28. The midpoint of the fifth switching element Q15 and the sixth switching element Q16 (the connection point between the source of the fifth switching element Q15 and the drain of the sixth switching element Q16) is the connection between the coil 26 and the coil 28 of the cargo handling motor 17. Connected to a point. The connection point B between the source of the first switching element Q11 and the drain of the second switching element Q12 is connected to the rectifier circuit 19 in the secondary winding 13d, which is the other single-phase output of the Scott transformer 13, by the wiring 21. It is connected to the terminal 16b opposite to the terminal 16a.

  The gates of the switching elements Q1 to Q6 and Q11 to Q16 are connected to the control device 22. The control device 22 is connected to current sensors S1 and S2 that detect a current flowing through the traveling motor 11 and current sensors S11 and S12 that detect a current flowing through the cargo handling motor 17. The control device 22 includes a CPU and a memory (not shown), and the memory stores a control program necessary for driving the traveling motor 11 and the cargo handling motor 17. The memory stores a control program necessary for controlling the switching elements Q1 to Q6 and Q11 to Q16 when the battery 30 is charged with the Scott transformer 13 connected to the three-phase AC power supply 40. Yes. Further, the control device 22 can detect the secondary current of the Scott transformer 13 (the charging current of the battery 30) based on signals from the current sensors S1, S2, S11, and S12.

  The motor drive system battery charging circuit includes a Scott transformer (single-phase output transformer) 13. The rectifier circuits 14 and 19 provided in the battery charging circuit of the motor drive system are connected to one terminals 15a and 16a of the secondary side output of the Scott transformer (single-phase output transformer) 13, and the inverters 12 and 18 and The battery 30 is connected in parallel. Current sensors S1 and S11 provided in the battery charging circuit of the motor drive system detect the current flowing between the connection points A and B and the motors 11 and 17. Wirings 20 and 21 provided in the battery charging circuit of the motor drive system are connected to the connection points A and B between the first switching elements Q1 and Q11 and the second switching elements Q2 and Q12 in the inverters 12 and 18 on the secondary side. The other terminals 15b and 16b of the output are connected.

Next, the effect | action of the vehicle-mounted apparatus 10 of this embodiment is demonstrated.
The battery forklift is held in a state disconnected from the three-phase AC power supply 40 except when the battery 30 is charged. Then, each of the switching elements Q1 to Q6 of the traveling inverter 12 is controlled to be turned on / off by a command from the control device 22, whereby the DC power of the battery 30 is converted to AC power and supplied to the traveling motor 11, The motor 11 is driven. Further, the switching elements Q11 to Q16 of the cargo handling inverter 18 are controlled to be turned on / off by a command from the control device 22, so that the DC power of the battery 30 is converted into AC power and supplied to the cargo handling motor 17 for cargo handling. The motor 17 is driven.

  When the in-vehicle device 10 is used as a charging device, the input and the output are electrically insulated by the Scott transformer 13, and the AC power as the in-vehicle power storage device connected to the output by converting the AC power as the input power to DC power is converted. The battery 30 is charged.

  At the time of charging, as shown in FIGS. 2 and 3, the control device 22 provided in the battery charging circuit of the motor drive system has two sets of switching elements Q3 constituting two phases (W phase and U phase) not connected to the transformer. , Q4, Q5, Q6, Q13, Q14, Q15, Q16 are synchronously controlled on / off. That is, the first switching elements Q1, Q11 and the second switching elements Q2, Q12 are held in the off state, and the third switching elements Q3, Q13 and the fifth switching elements Q5, Q15 are controlled on / off in synchronization with the first switching elements Q1, Q11. The 4 switching elements Q4 and Q14 and the sixth switching elements Q6 and Q16 are controlled to be turned on / off in synchronization.

  Specifically, when the battery 30 is charged, the Scott transformer 13 is held in a state where AC power is supplied from the three-phase AC power supply 40. Specifically, the plug of the charging cable of the three-phase AC power supply 40 is connected to a power outlet provided on the forklift. Then, the control device 22 keeps the switching elements Q1, Q2, Q11, Q12 of the traveling inverter 12 and the cargo handling inverter 18 in the off state, the third switching elements Q3, Q13, the fourth switching elements Q4, Q14, The fifth switching elements Q5 and Q15 and the sixth switching elements Q6 and Q16 are turned on / off. That is, the switching element for the upper arm and the switching element for the lower arm that are PWM-controlled when the battery 30 is charged by the control device 22 are switching elements Q3, Q13, Q4, Q14, Q5, Q15, Q6, Q16. Become. Further, the switching elements for the upper arm and the switching elements for the lower arm that are not PWM-controlled when the battery 30 is charged by the control device 22 are switching elements Q1, Q2, Q11, and Q12.

  The control device 22 switches the third switching elements Q3 and Q13, the fourth switching elements Q4 and Q14, the fifth switching elements Q5 and Q15, and the sixth switching elements Q6 and Q16 in the traveling inverter 12 and the cargo handling inverter 18. To do. Thus, the battery 30 is charged using the coils 23 and 24 of the traveling motor 11 and the coils 26 and 27 of the cargo handling motor 17 as charging inductors.

  A path of a current flowing through the in-vehicle device 10 when the battery 30 is charged will be described with reference to FIGS. 2 and 3, the current path for charging the battery 30 by controlling the switching elements Q3, Q4, Q5, and Q6 of the traveling inverter 12 is described. However, the switching element of the cargo handling inverter 18 is described. The same route is used when charging the battery 30 by controlling Q13, Q14, Q15, and Q16.

  As shown in FIG. 2, the switching elements Q3 and Q5 are in the on state, the switching elements Q4 and Q6 are in the state where electric power is output from the terminal 15a of one secondary winding 13c of the Scott transformer 13 on the traveling inverter 12 side. When is turned off, current flows as shown by a broken line in FIG. That is, the terminal 15a of the secondary winding 13c → the diode D1 → the third switching element Q3 → the coil 24 of the traveling motor → the path of the terminal 15b of the secondary winding 13c and the terminal 15a of the secondary winding 13c → the diode. A current flows through a route of D1 → the fifth switching element Q5 → the coil 23 of the traveling motor → the terminal 15b of the secondary winding 13c. At this time, electromagnetic energy is accumulated in the coils 23 and 24.

  When the switching elements Q4 and Q6 are turned on, the electromagnetic energy accumulated in the coils 23 and 24 becomes a current that flows along a path indicated by a one-dot chain line in FIG. That is, the coil 24 of the traveling motor 11 → the terminal 15b of the secondary winding 13c → the terminal 15a of the single-phase output 13c → the diode D1 → the battery 30 → the fourth switching element Q4 → the path of the coil 24 of the traveling motor 11; In addition, in the path of the coil 23 of the traveling motor 11 → the terminal 15b of the secondary winding 13c → the terminal 15a of the single-phase output 13c → the diode D1 → the battery 30 → the sixth switching element Q6 → the coil 23 of the traveling motor 11 It becomes the flowing current. At this time, the battery 30 is charged.

  As shown in FIG. 3, when power is output from the terminal 15b of the secondary winding 13c, when the switching elements Q3 and Q5 are in the off state and the switching elements Q4 and Q6 are in the on state, a broken arrow in FIG. Current flows as shown by. That is, the terminal 15b of the secondary winding 13c → the coil 24 of the traveling motor 11 → the fourth switching element Q4 → the diode D2 → the path of the terminal 15a of one secondary winding 13c and the terminal of the secondary winding 13c Current flows through a path of 15b → coil 23 of the motor 11 for traveling → sixth switching element Q6 → diode D2 → terminal 15a of one secondary winding 13c. At this time, electromagnetic energy is accumulated in the coils 23 and 24. When the switching elements Q3 and Q5 are turned on, the electromagnetic energy accumulated in the coils 23 and 24 becomes a current that flows along a path indicated by a one-dot chain line arrow in FIG. That is, the coil 24 of the traveling motor 11 → the third switching element Q3 → the battery 30 → the diode D2 → the terminal 15a of the secondary winding 13c → the terminal 15b of the secondary winding 13c → the path of the coil 24 of the traveling motor 11 And the path of the coil 23 of the traveling motor 11 → the coil 23 of the traveling motor 11 → the fifth switching element Q5 → the battery 30 → the diode D2 → the terminal 15a of the secondary winding 13c → the terminal 15b of the secondary winding 13c. It becomes the flowing current. At this time, the battery 30 is charged.

  During charging, the current sensors S2 and S12 are used as abnormality detection sensors for detecting overcurrent and the like. Further, during charging, the current sensors S1 and S11 are also used as abnormality detection sensors for detecting an overcurrent or the like.

  Further, charging is performed also on the cargo handling inverter 18 side in the same manner as the traveling inverter 12. Specifically, the secondary winding 13c on the traveling inverter 12 side is the secondary winding 13d, the terminals 15a and 15b are the terminals 16a and 16b, the third switching element Q3 is the third switching element Q13, and the fourth If switching element Q4 is replaced with fourth switching element Q14, fifth switching element Q5 is replaced with fifth switching element Q15, sixth switching element Q6 is replaced with sixth switching element Q16, and diodes D1 and D2 are replaced with diodes D3 and D4, respectively. Good.

Rather than providing a current sensor for each phase, only one phase (W phase) of the two phases (W phase, U phase) to be turned on / off is attached.
In addition, the switching elements (MOSFETs) Q1 to Q6 and Q11 to Q16 have variations because the dead time, that is, the delay from the command to the actual operation (time until turn-on and turn-off) is not uniform. In order to correct the above, the following control is performed before charging is started.

  As shown in FIGS. 4 and 5, the control device 22 performs on / off control of the third switching element Q <b> 3 to set the current value by the current sensor S <b> 1 in a state in which the second switching element Q <b> 2 is controlled, as shown in FIGS. And the second duty by the on / off control of the fifth switching element Q5 to set the current value by the current sensor S1 to the specified value, and the current value by the current sensor S1 in a state where the first switching element Q1 is controlled. The third duty by the on / off control of the fourth switching element Q4 to be the specified value and the fourth duty by the on / off control of the sixth switching element Q6 to set the current value by the current sensor S1 to the specified value are acquired.

  Further, the first duty, the second duty, the third duty, and the fourth duty are also acquired on the cargo handling inverter 18 side in the same manner as the traveling inverter 12. Specifically, the first switching element Q1 on the traveling inverter 12 side is the first switching element Q11, the second switching element Q2 is the second switching element Q12, the third switching element Q3 is the third switching element Q13, The fourth switching element Q4 can be replaced with the fourth switching element Q14, the fifth switching element Q5 can be replaced with the fifth switching element Q15, the sixth switching element Q6 can be replaced with the sixth switching element Q16, and the current sensor S1 can be replaced with the current sensor S11. That's fine.

This will be described in detail with reference to FIGS.
Before starting charging, energize in the following patterns (the energization path indicated by the broken line in FIG. 4, the energization path indicated by the dashed line in FIG. 4, the energization path indicated by the broken line in FIG. 5, and the energization path indicated by the dashed line in FIG. 5). The duty correction amount of the switching element for equalizing the two-phase current is acquired.

  As pattern 1, the switching element Q2 for the V-phase lower arm is fixed in the ON state, and the switching element Q3 for the W-phase upper arm is chopper-controlled. The current path is battery 30 → switching element Q3 → coil 24 → switching element Q2 → battery 30 as indicated by a broken line in FIG. At this time, the switching element Q3 for the W-phase upper arm is chopper-controlled so that the detected current value by the V-phase current sensor S1 becomes a specified value + α [A]. Note that + in + α [A] represents the direction of current flow. The duty of switching element Q3 for W-phase upper arm at this time is defined as a first duty (DutyWαn [%]).

  As the pattern 2, the switching element Q2 for the V-phase lower arm is fixed in the ON state (same as the energization current in the pattern 1), and the switching element Q5 for the U-phase upper arm is chopper-controlled. The current path is battery 30 → switching element Q5 → coil 23 → switching element Q2 → battery 30 as indicated by a one-dot chain line in FIG. At this time, the switching element Q5 for the U-phase upper arm is chopper-controlled so that the detected current value by the V-phase current sensor S1 becomes the specified value + α [A]. The duty of the switching element Q5 for the U-phase upper arm at this time is defined as a second duty (DutyUαn [%]).

  As pattern 3, the switching element Q1 for the V-phase upper arm is fixed in the ON state, and the switching element Q4 for the W-phase lower arm is chopper-controlled. The current path is battery 30 → switching element Q1 → coil 24 → switching element Q4 → battery 30 as indicated by a broken line in FIG. At this time, the switching element Q4 for the W-phase lower arm is chopper-controlled so that the detected current value by the V-phase current sensor S1 becomes −α [A] which is a specified value. In addition,-of [alpha] [A] represents the direction of current flow. The duty of switching element Q4 for the W-phase lower arm at this time is defined as a third duty (DutyWαp [%]).

  As the pattern 4, the switching element Q1 for the V-phase upper arm is fixed in the ON state (same as the energization current in the pattern 3), and the switching element Q6 for the U-phase lower arm is chopper-controlled. The current path is battery 30 → switching element Q1 → coil 23 → switching element Q6 → battery 30 as indicated by a one-dot chain line in FIG. At this time, the switching element Q6 for the U-phase lower arm is chopper-controlled so that the current value detected by the V-phase current sensor S1 becomes −α [A] which is a specified value. The duty of the switching element Q6 for the U-phase lower arm at this time is the fourth duty (DutyUαp [%]).

  In this way, the first, second, third, and fourth duties are acquired, and the control device 22 sets the third switching element Q3 and the fifth switching element Q5 to the first duty and the first duty after the start of charging. On / off control is performed while correcting with 2 duty, and on / off control is performed with 4th switching element Q4 and 6th switching element Q6 being corrected with 3rd duty and 4th duty.

Details are as follows.
During charging, the U-phase switching duty is controlled by adding the following correction amount to the W-phase switching duty.

  When the current is in the + direction shown in FIG. 2, U phase duty = W phase duty + (DutyUαn−DutyWαn). That is, the difference between the second duty (DutyUαn [%]) and the first duty (DutyWαn [%]) is added to the W-phase duty as the U-phase duty.

  On the other hand, when the current is in the negative direction shown in FIG. 3, U phase duty = W phase duty + (DutyUαp−DutyWαp). That is, the difference between the fourth duty (DutyUαp [%]) and the third duty (DutyWαp [%]) is added to the W-phase duty as the U-phase duty.

  By making corrections in this way, it is possible to acquire and correct variations between phases without adding elements, sensors, etc. by devising a switching pattern and flowing current before starting charging. Become. That is, the battery charging current can be accurately controlled by acquiring and correcting the variation between phases before the start of charging.

  That is, when two sets of switching elements constituting two phases not connected to the transformer of the three-phase inverter are controlled on / off in synchronization, it is conceivable to provide a current sensor for each phase. If the current sensor is attached to only one of the two phases to be turned off, the two-phase current cannot be controlled equally due to variations in the dead time between the switching elements, and there is an error in the battery charging current. Occur. In the present embodiment, when the same current is supplied at the time of charging, correction is performed based on the difference in duty of the switching element acquired before the start of charging, so that this can be avoided and the battery charging current can be accurately controlled.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The patterns for obtaining the duty correction amount of the switching element are four patterns (the energization path indicated by the broken line in FIG. 4, the energization path indicated by the one-dot chain line in FIG. 4, the energization path indicated by the broken line in FIG. 5, and the one-dot chain line in FIG. The energization path indicated by The following four patterns (patterns 5, 6, 7, and 8) may be further added to the patterns 1, 2, 3, and 4. That is, the following four patterns may be added after energizing with not only one pattern but two large and small currents, that is, ± α [A].

  As pattern 5, the switching element Q2 for the V-phase lower arm is fixed in the ON state as in the current path shown by the broken line in FIG. 4 so that the detected current value by the V-phase current sensor S1 becomes + β [A]. The switching element Q3 for the W-phase upper arm is chopper-controlled. The duty of switching element Q3 for the W-phase upper arm at this time is the fifth duty (DutyWβn [%]).

  As the pattern 6, the switching element Q2 for the V-phase lower arm is fixed in the ON state as in the current path shown by the one-dot chain line in FIG. 4, and the detected current value by the V-phase current sensor S1 becomes + β [A]. The chopper control is performed on the switching element Q5 for the U-phase upper arm. At this time, the duty of the switching element Q5 for the U-phase upper arm is defined as a sixth duty (DutyUβn [%]).

  As the pattern 7, the switching element Q1 for the V-phase upper arm is fixed in the ON state as in the current path indicated by the broken line in FIG. 5, and the detected current value by the V-phase current sensor S1 becomes −β [A]. Then, the switching element Q4 for the W-phase lower arm is chopper-controlled. The duty of the switching element Q4 for the W-phase lower arm at this time is defined as a seventh duty (DutyWβp [%]).

  As the pattern 8, the switching element Q1 for the V-phase upper arm is fixed in the ON state as in the current path shown by the one-dot chain line in FIG. 5, and the detected current value by the V-phase current sensor S1 becomes −β [A]. Thus, the switching element Q6 for the U-phase lower arm is chopper-controlled. The duty of the switching element Q6 for the U-phase lower arm at this time is the eighth duty (DutyUβp [%]).

  In FIG. 6, the horizontal axis represents the current command value and the vertical axis represents the correction value. As shown in FIG. 6, the correction value for the current command value α is (DutyUαp−DutyWαp), that is, the first duty that is the difference between the fourth duty (DutyUαp [%]) and the third duty (DutyWαp [%]). Correction value P1 is obtained as a plot point. Further, as a correction value for the current command value β, (DutyUβp−DutyWβp), that is, a second correction value P2 that is a difference between the eighth duty (DutyUβp [%]) and the seventh duty (DutyWβp [%]). Get as plot points.

From the characteristic line L1 that connects the two points (first correction value P1 and second correction value P2), the correction amount is interpolated and applied according to the current that flows during charging.
Similarly, as a correction value for the current command value α, (DutyUαn−DutyWαn), that is, the difference between the second duty (DutyUαn [%]) and the first duty (DutyWαn [%]) is obtained as a plot point. Further, as a correction value for the current command value β, (DutyUβn−DutyWβn), that is, the difference between the sixth duty (DutyUβn [%]) and the fifth duty (DutyWβn [%]) is obtained as a plot point. From the characteristic line connecting these two points, the correction amount is interpolated according to the current that flows during charging.

  In this way, the first correction value P1 according to patterns 1 to 4 when α is taken as the current command value on the horizontal axis in FIG. 6 and the pattern 5 when β is taken as the current command value on the horizontal axis in FIG. A second correction value P2 of 8 is obtained. The characteristic line L1 is a straight line passing through the first correction value P1 and the second correction value P2. Then, the correction value is calculated by linear interpolation from the target current value using the characteristic line L1.

  By doing in this way, the fluctuation | variation of load (motor coil) can also be correct | amended collectively by making the electric current at the time of correction amount acquisition into two types, large and small. The same applies to the cargo handling inverter 18 side.

  In this way, the control device 22 sets the current value by the current sensors S1 and S11 in a state in which the second switching elements Q2 and Q12 are controlled to a specified value different from that when the first duty is acquired before the start of charging. The fifth switching elements Q5, Q15 are turned on / off by setting the fifth duty by the on / off control of the third switching elements Q3, Q13 and the current value of the current sensors S1, S11 different from those obtained when the second duty is acquired. The fourth switching element Q4 having the sixth duty by the off control and the current value by the current sensors S1 and S11 in a state in which the first switching elements Q1 and Q11 are controlled is different from the value obtained when the third duty is acquired. The seventh duty by the on / off control of Q14 and the current value by the current sensors S1, S11 are The eighth duty is obtained by the on / off control of the sixth switching elements Q6 and Q16 that have a specified value different from that when the duty is obtained, and after the start of charging, the third switching elements Q3 and Q13 and the fifth switching element are switched. The elements Q5 and Q15 are turned on / off while being corrected by the first duty, the second duty, the fifth duty, and the sixth duty, and the fourth switching elements Q4 and Q14 and the sixth switching elements Q6 and Q16 are set to the third duty. On / off control may be performed while correcting with the fourth duty, the seventh duty, and the eighth duty.

  When acquiring the switching duty correction amount, in the above-described patterns 1 to 4 or the above-described patterns 1 to 8, the V-phase upper arm first switching elements Q1, Q11 to the lower arm second switching element Q2, Q12 may be switched at a certain duty without being fixed on. In other words, since the energization current is reduced by adjusting the input voltage, the on-time of the duty is lengthened, so that an error can be detected with high accuracy. As described above, the duty of the switching elements Q1, Q2, Q11, and Q12 for V-phase when acquiring the correction amount is not fixed to 100% on, but is controlled to a constant amount, so that the dispersion is desired for U-phase and W-phase. The duty of the switching elements Q3 to Q6 and Q13 to Q16 is relatively increased, and the accuracy of acquiring the correction amount is improved.

The battery 30 may be charged using either the traveling inverter 12 or the cargo handling inverter 18.
○ A transformer other than the Scott transformer 13 may be used.

  A vehicle-mounted device provided with a three-phase motor (travel motor 11 and cargo handling motor 17) such as a battery forklift is used as a charging device, but it may be applied to a charging device for a general electric vehicle.

  ○ Although applied to forklifts, it may be applied to other industrial vehicles. Moreover, you may apply to vehicles other than an industrial vehicle, for example, a passenger car, a bus | bath, etc.

  DESCRIPTION OF SYMBOLS 11 ... Traveling motor (three-phase motor), 12 ... Traveling inverter (three-phase inverter), 13 ... Scott transformer, 14 ... Rectifier circuit, 15a ... Terminal, 15b ... Terminal, 16a ... Terminal, 16b ... Terminal, 17 ... Cargo handling motor (three-phase motor), 18 ... Cargo handling inverter (three-phase inverter), 19 ... Rectifier circuit, 20 ... Wiring, 21 ... Wiring, 22 ... Control device, 30 ... Battery, A ... Connection point, B ... Connection Point, S1, S11 ... current sensor, Q1, Q11 ... first switching element, Q2, Q12 ... second switching element, Q3, Q13 ... third switching element, Q4, Q14 ... fourth switching element, Q5, Q15 ... first 5 switching elements, Q6, Q16 ... 6th switching element.

Claims (2)

First switching element for upper arm of first phase, second switching element for lower arm of first phase, third switching element for upper arm of second phase, fourth switching for lower arm of second phase Motor drive comprising a three-phase motor driven by a battery as a power source by a three-phase inverter having an element, a fifth switching element for the upper arm of the third phase, and a sixth switching element for the lower arm of the third phase Battery charging circuit of the system,
A single-phase output transformer,
A rectifier circuit connected to one terminal of the secondary side output of the single-phase output transformer and connected in parallel to the three-phase inverter and the battery;
Wiring connecting a connection point between the first switching element and the second switching element in the three-phase inverter to the other terminal of the secondary output;
At the time of charging, the first switching element and the second switching element are held in an off state, and the third switching element and the fifth switching element are controlled to be turned on / off in synchronization, and the fourth switching element and the sixth switching element are controlled. A control device for controlling on / off of the switching element in synchronization;
A current sensor for detecting a current flowing between the connection point and the three-phase motor;
With
The controller is
Before starting charging, the current value by the current sensor in a state in which the second switching element is controlled is set to a specified value. The first duty by the on / off control of the third switching element and the current value by the current sensor are specified values. ON / OFF control of the fourth switching element to set a second duty by ON / OFF control of the fifth switching element to be set to a specified value and a current value by the current sensor in a state in which the first switching element is controlled And a fourth duty by the on / off control of the sixth switching element for setting the current value by the current sensor and the current value by the current sensor to a specified value,
After the start of charging, the third switching element and the fifth switching element are on / off controlled while being corrected by the first duty and the second duty, and the fourth switching element and the sixth switching element are A battery charging circuit that performs on / off control while correcting with the third duty and the fourth duty. The controller is
Before the start of charging, a fifth value is set by on / off control of the third switching element so that the current value of the current sensor in a state in which the second switching element is controlled is set to a specified value different from that when the first duty is acquired. A state in which the first switching element is controlled, and the sixth duty by the on / off control of the fifth switching element to set the duty and the current value by the current sensor to a specified value different from that at the time of obtaining the second duty The current value by the current sensor is set to a specified value different from that when the third duty is acquired. The seventh duty by the on / off control of the fourth switching element and the current value by the current sensor are set to the fourth duty. For the on / off control of the sixth switching element that has a specified value different from that obtained Eighth in advance to get the duty that,
After the start of charging, the third switching element and the fifth switching element are on / off controlled while being corrected by the first duty, the second duty, the fifth duty, and the sixth duty, and the fourth switching element 2. The battery charging according to claim 1, wherein the switching element and the sixth switching element are on / off controlled while being corrected by the third duty, the fourth duty, the seventh duty, and the eighth duty. circuit.

Images